The process is manifest in the Antarctic peninsula, which has been shown to be the region of the continent that is most at risk to global warming.

“The common house fly is a perfect example of the problem the Antarctic now faces from invading species,” said Dominic Hodgson of the British Antarctic Survey.

“It comes in on ships, where it thrives in kitchens and then at bases on the continent. It now has an increasing chance of surviving in the Antarctic as it warms up, and that is a worry. Insects like the fly carry pathogens that could have a devastating effect on indigenous lifeforms.”

The Antarctic has several native species of insects. Together with its indigenous mosses and lichens, these are now coming under increased threat from three major sources: visiting scientists; swelling numbers of tourists; and global warming.

In 2015-16, more than 38,000 tourists visited Antarctica while around 43,000 were expected for the following season.

“These tourists are often very scrupulous about not leaving waste or having mud – which could carry seeds or bugs from other areas – on their boots when they set foot on the Antarctic peninsula,” said Hodgson.

“However, it is still very difficult to avoid contamination. Camera bags are a particular problem. People take them from one continent to the next and rarely clean them. They put them on the ground and seeds picked up elsewhere get shaken loose. It is a real issue.”

Nevertheless, it is global warming that is the main driver of the greening of Antarctica.

Temperatures have been rising steadily in the peninsula since meteorological data began to be collected there in the 1950s.

This shows that over the past 60 years the region has warmed up by around half a degree Celsius every decade.As a result, the Antarctic’s scarce plant life – which currently grows on only 0.3% of the continent – has responded dramatically, according to British researchers writing in Current Biology.